General Principles Of Instrumentation

Fffective instrumentation is governed by a number of general principles that are common to all periodontal instruments. Proper position of the patient and the operator. illumination and retraction for optimal visibility, and sharp instruments are fundamental prerequisites. A constant awareness of tooth and root morphologic features and of the condition of the periodontal tissues is also essential. Knowledge of instrument design enables the clinician to efficiently select the proper instrument for the procedure and the area in which it will be performed. In addition to these principles, the basic concepts of grasp, linger rest, adaptation, angulation, and stroke must be understood before clinical instrument-handling skills can he mastered.

Accessibility (Positioning of Patient and Operator)

Accessibility facilitates thoroughness of instrumentation. I he position of the patient and operator should provide maximal accessibility to the area of operation. Inadequate accessibility impedes thorough instrumentation, prematurely tires the operator, and diminishes his or her effectiveness.

The clinician should be seated on a comtortable operating stool that has been positioned so th.it his or her feet are flat on the lloor with the thighs parallel to the lloor. The clinician should he able to observe the held of oj)era-tion while keeping the back straight and the head erect.

The patient should he in .1 supine position and placed so that the mouth is close to the resting elbow of the clinician. For instrumentation of the maxillary arch, the patient should be asked to raise his or her chin slightly to provide optimal visibility and accessibility. For instrumentation on the mandibular arch, it may be necessary to raise the back of the chair slightly and request that the patient lower his or her chin until the mandible is parallel to the lloor. I his will especially facilitate work on the lingual surfaces of the mandibular anterior teeth.

Visibility, Illumination, and Retraction

Whenever possible, direct vision with direct illumination from the dental light is most desirable d ig. 12-1). If this is not possible, indirect vision mas be obtained by using the mouth mirror d ig. 42-2). and indirect illumination may be obtained by using the mirror to reflect light to where it is needed (Fig. 42-/5). Indirect vision and indirect illumination are often used simultaneously (I ig. 12-4).

Retraction provides visibility, accessibility, and illumination. Depending on the location of the area of operation. the lingers and/or the mirror are used tor retraction. I he mirror may he used lor retraction <>t the cheeks

Mil i mili histiiintcnUitum ■ ( II\IM IK 42 595

Fig. 42-1 Direct vision and direct illumination in the mandibular left premolar area.

Fig. 42-2 Indirect vision using the mirror for the lingual surfaces of the mandibular anterior teeth.

Fig. 42-4 Combination of indirect illumination and indirect vision for the lingual surfaces of the maxillary anterior teeth.

Fig. 42-2 Indirect vision using the mirror for the lingual surfaces of the mandibular anterior teeth.

Fig. 42-4 Combination of indirect illumination and indirect vision for the lingual surfaces of the maxillary anterior teeth.

or the tongue; the index linger is used lor retraction of the lips or cheeks. The following methods are effective for retraction:

1. Use of the mirror to deflect the cheek while the fingers of the nonoperating hand retract the lips and protect the angle of the mouth from irritation by the mirror handle

2. Use of the mirror alone to retract the lips and cheek (Fig. 42-5)

3. Use of the fingers of the nonoperating hand to retract the lips (Fig. 42-6)

4. Use of the mirror to retract the tongue d ig. 42-7)

5. Combinations ol the preceding methods

When retracting, care should he taken to avoid irritation to the angles of the mouth. If the lips and skin are dry, softening the lips with petroleum jelly helore instrumentation is begun is a helpful precaution against cracking and bleeding. ( .'a ret til retraction is especially important for patients with a history of recurrent ! wipes lubiiilis, because these patients may easily develop herpetic lesions after instrumentation.

Condition of Instruments (Sharpness)

Before any instrumentation, all instruments should be inspected to make sure that they arc- clean, sterile, and in good condition. I lie working ends ol pointed or hladcd

Fig. 42-6 Retracting the lip with the index finger of the nonoper- Fig. 42-8 Modified pen grasp. The pad of the middle linger rests ating hand. on the shank.

Fig. 42-5 Retracting the cheek with the mirror.

Fig. 42-6 Retracting the lip with the index finger of the nonoper- Fig. 42-8 Modified pen grasp. The pad of the middle linger rests ating hand. on the shank.

Fig. 42-5 Retracting the cheek with the mirror.

Fig. 42-7 Retracting the tongue with the mirror.

instruments must be sharp to he effective. Sharp instruments enhance tactile sensitivity and allow the clinician to work more precisely and efficiently. Dull instruments may lead to incomplete calculus removal and tinneecs-sar\ trauma because of the excess force usually applied to compensate lor their ineffectiveness (see < hapter 41).

Maintaining a Clean Field

Despite good visibility, illumination, and retraction, instrumentation can be hampered it the operative field is obscured by saliva, blood, and debris. The pooling of saliva interferes with visibility during instrumentation and impedes control because a firm finger rest cannot be established on wet, slippery tooth surfaces. Adequate suction is essential and can be achieved with a saliva ejector or. it working with «in assistant, an aspirator.

Gingival bleeding is an unavoidable consequence of subgingival instrumentation. In areas ot inflammation this is not necessarily an indication of trauma from incorrect technique; instead, it indicates ulceration of the pocket epithelium. Blood and debris can be removed from the operatise field with suction and l>\ wiping or blotting with gauze squares. I he operative field should also be Hushed occasionally with water

Compressed air and gauze squares can be used to facilitate visual inspection of tooth surfaces just below the gingival margin during instrumentation. A jet of air directed into I lie poc ket deflec ts a retrai table gingival margin. Retractable tissue can also be deflected away from the tooth by gently packing the edge ol a gauze square into the pocket with the back ol a curette. Immediately after the gauze is removed, the subgingiv.il area should be clean, dry. and clearly visible for a brief interval.

Manual Instrumentation ■ ( IIAIMI K 42 597

Fig. 42-9 Standard pen grasp. The side of I he middle finger rests on the shank.

Instrument Stabilization

Stability of the instrument and I he hand is the primary requisite for controlled instrumentation. Stability and control are essential for effective instrumentation and avoidance of injury to the patient or clinician. T he two factors of major importance in providing stability are the instrument grasp and the linger rest.

Instrument Grasp. A proper grasp is essential for precise control of movements made during periodontal instrumentation. I lie most effective and stable grasp for all periodontal instruments is the modified pen grasp ilig. 42-8). Although other grasps are possible, this moditka-tion of the standard pen grasp (f ig. 42-9) ensures the greatest control in performing Intraoral procedures.

The thumb, index finger, and middle finger are used to hold the instrument as a pen is held, but the middle finger is positioned so thai the side of the pad next to the fingernail is resting on the instrument shank. The index finger is bent at the second joint from the finger tip and is positioned well above the middle linger on the same side of the handle.

The pad of the thumb is placed midway between the middle and index lingers on the opposite side of the handle. This creates a triangle of forces, or tripod effect, that enhances control because it counteracts the tendency of the instrument to turn uncontrollably between the lingers when scaling force is applied to the tooth. I bis stable modified pen grasp enhances control because it enables the clinician to roll the instrument in precise degrees with the thumb against the index and middle lingers to adapt the blade to the slightest changes in tooth contour. I he modified pen grasp also enhances tactile sensitivity, because slight irregularities on the tooth surface are best perceived when the tactile-sensitive pad (»1 the middle linger Is placed on the shank of the instrument.

The palm and thumb grasp (Fig. 42-10) is useful lor stabilizing instruments during sharpening and lor manipulating air and water syringes, but it is not recommended tor periodontal instrumentation. Maneuverability and tactile sensitivity are so inhibited by this grasp that it is unsuitable for the precise, controlled movements necessary during periodontal procedures.

l inger Rest. the linger rest serves to stabilize the hand and the instrument by providing a firm fulcrum as movements ¿»re made to activate the instrument \ good linger rest prevents injury and laceration of the gingiva and surrounding tissues by poor I \ controlled instruments The fourth (ring) linger is preferred b\ most clinicians for the linger rest. Although it is possible to use the third (middle) linger lor the linger rest, this is not recommended. because it restricts the arc ol movement during the activation ol strokes and severely curtails the use ol the middle linger lor both control and tactile sensitivity. Maximal control is achieved when the middle linger is kept between the instrument shank and the fourth finger Ibis "built-up" fulcrum is an integral part of the wrist-forearm action that activates the powerful working stroke for calculus removal. Whenever possible, these two lingers should be kept together to work as a one-unit fulcrum during scaling and root planing. Separation ol the middle and lourth lingers during scaling strokes results in .i loss of power and control because it forces the clinician to rely solely on linger flexing lor ai ti vat ion of the instrument.

l inger rests may be generally classified as intraoral linger rests or extraoral fulcrums. Intraoral finger rests on tooth surfaces ideally «ire established close to the working area. Variations ol intraoral linger rests and extraoral fulcrums «ire used whenever good angulation and «i sulhcient arc ol movement cannot be achieved by a linger rest closc to the working area. I'he following examples illus-trate the different variations of the intraoral linger rest:

1. Conventional: I he linger rest is established on tooth surfaces immediatel) adjacent to the working area (Fig. 42-11).

2. Crass-anh: The linger rest is established on tooth sur-faces on the other side of the same arch (l ig. 42-12).

/5. Opposite-arch: I he linger rest is established on tooth surfaces on the opposite arch (e.g., mandibular arch linger rest for instrumentation on the maxillary arch) d ig. 42-13).

4. fingcr-on-pnger: I he linger rest is established on the index linger or thumb ol the nonoperating hand (Fig. 42-14).

F.xtraoral fulcrums are essential tor effective instrumentation of some aspects ol the maxillary posterior teeth. When properly established, they allow optimal access and angulation while providing adequate stabilization. hxtraoral fulcrums are not linger rests in the literal sense, because the tips or pads of the lingers are not used for extraoral fulcrums as they are for intraoral finger rests. Instead, as much ol the front or back surface of

Fig. 42-12 Iniraoral cross-arch finger rest The fourth linger rests on the incisal surfaces ol teeth on the opposite side of the same arch.

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the fingers as possible is placed on the patient's face to provide the greatest degree of stability. The two most commonly used extraoral fulcrums are as follows:

1. Patni-up: The palm-up fulcrum is established by resting the backs of the middle and fourth lingers on the skin overlying the lateral aspect of the mandible on the right side ol the face (Fig. 42-15).

2. Palm-down: The palm-down fulcrum is established by resting the tront surfaces ol the middle and fourth fingers on the skin overlying the lateral aspect of the mandible on the left side of the lace (Fig. 42-10).

Both intraoral finger rests and extraoral lulcrums may be reinforced by applying the index linger or thumb of the nonoperating hand to the handle or shank of the instrument for added control and pressu.j against the tooth. I he reinforcing linger is usually employed for opposite-arch or extraoral fulcrums when precise control and pressure are compromised In the longer distance between the lulcrum and the working end of the instrument. I ig. 42-17 shows the index fin-ger-reinlorced rest, and I ig. 42-1S shows the thumb-reinforced rest.

Fig. 42-15 Extraoriil palm-up lulcrum. The backs ol the fingers rest on the right lateral aspect ol the mandible while the maxillary right posterior teeth are instrumented.

Fig. 42-17 Index finger-reinforced rest, the index finger is placed on the shank lor pressure and control in the maxillary left posterior lingual region.

Fig. 42 18 Thumb-reinforced rest. The thumb is placed on the handle lor control in the maxillary right posterior lingual region.

Fig. 42-16 Extraoral palm-down fulcrum. The tront surlaces ol the fingers rest on the left lateral aspect ol the mandible while the maxillary lelt posterior teeth are instrumented.

Fig. 42 18 Thumb-reinforced rest. The thumb is placed on the handle lor control in the maxillary right posterior lingual region.

Instrument Activation

Adaptation. Adaptation refers to I he manner in which the working end of a periodontal instrument is placed against the surface of a tooth. The objective of adaptation is to make the working end of the instrument conform to the contour of the tooth surface. Precise adaptation must be maintained with all instruments to avoid trauma to the soft tissues and root surfaces and to ensure maximum effectiveness of instrumentation.

Correct adaptation of the probe is quite simple. The tip and side of the probe should be Hush against the tooth surface as vertical strokes arc activated within the crevice, bladed instruments such as curettes and sharp-pointed instruments such as explorers are more difficult to adapt. I'he ends of these instruments are sharp and can lacerate tissue, so adaptation in subgingival areas he-comes especially important. The lower third of the working end, which is the last few millimeters adjacent to the toe or tip, must be kept in constant contact with the tooth while it is moving over varying tooth contours (Fig. 42-19). Precise adaptation is maintained by care-fulls roiling the handle of the instrument against the index and middle lingers with the thumb. I'his rotates the instrument in slight degrees so that the toe or tip leads into concavities and around convexities. On convex stu-faces such as line angles, it is not possible to adapt more than I or 2 mm of the working end against the tooth. Fven on what appear to he broader, Hatter surfaces, no more than I or 2 mm of the working end can be adapted, because the tooth surface, although it may seem Hal, is actually slightly curved.

II only the middle third of the working end is adapted on a convex surface so that the blade contacts the tooth at a tangent, the toe or sharp tip will jut out into soft tissue, causing trauma and discomfort (Fig. 42-201. if the instrument is adapted so that only the toe or tip is in contact, the soft tissue can be distended or compressed by the back ol the working end, also causing trauma and

Fig. 42-19 Cracey curette blade divided into three segments: the lower one third ol the blade, consisting of the terminal few millimeters adjacent to the toe (A); the middle one third (B); and the upper one third, which is adjacent to the shank (C).

discomfort. A curette that is improperly adapted in this manner can he particularly damaging, because the toe can gouge or groove the root surface.

Angulation. Angulation refers to the angle between the face ol a bladed instrument and lite tooth surlace. It may also be called the tooth-blade relationship.

Correct angulation is essential tor effective calculus removal. For subgingival insertion ol a bladed instrument such as a curette, angulation should be .is close to (I degree as possible II ig. 42-21). File end of the instrument can be inserted to the base ol the pocket more easily with the face of the blade flush against the tooth. During scaling and root planing, optimal angulation is between 45 and 90 degrees (see Fig. 42-21). I he exact blade angulation depends oil the amount and nature of the calculus, the procedure being performed, and the condition ol the tissue. Blade angulation is diminished or closed by tilting the lower shank of the instrument toward the tooth. It is increased or opened by tilting the lower shank away from the tooth. During scaling strokes on heavy, tenacious calculus, angulation should be just less than 90 degrees so that the cutting edge "bites" into the calculus. With angulation ol less than 45 degrees, the cutting edge will not bite into or engage the calculus properly (see I ig. 42-21). Instead, it will slide over the calculus, smoothing or "burnishing" it. It angulation is more than 90 degrees, the lateral surface ol the blade, rather than the cutting edge, will be against the tooth, and the calculus will not he removed and may become burnished (see I ig. 42-21). Alter the calculus has been removed, angulation of just less than 90 degrees may be maintained, or the angle may be slightly closed as the root surface is smoothed with light root planing strokes.

When gingival curettage is indicated, angulation greater than 90 degrees is deliberately established so that the cutting edge will engage and remove the pocket lining (see l ig. 42-21).

Fig. 42-20 Blade adaptation. The curette on the left is properly adapted to the root surface. The curette on the right is incorrectly adapted; the toe juts out, lacerating the soft tissues.

Lateral Pressure. Lateral pressure refers to the pressure aealeil when force is applied against the surface of a tooth with Ihe cutting edge of a bladed instrument. Ihe exact amount of pressure applied must he varied according to the nature of the calculus and according to whether the stroke is intended for initial scaling to remove calculus or tor root planing to smooth the root surface.

lateral pressure may he firm, moderate, or light. When removing calculus, lateral pressure is applied firmly or moderated initial!) and is progressively diminished until light lateral pressure is applied for the final root planing strokes. When insufficient lateral pressure is applied for the removal of heavy calculus, rough ledges or lumps may he shaved to thin, smooth sheets of burnished calculus that are difficult to detect and remove. This burnishing effect often occurs in areas of developmental depressions and along the cementoenamel junction (( k|).

The careful application of varied and controlled amounts of lateral pressure during instrumentation is an integral part of effective scaling and root planing techniques and is absolutely critical to the success of both of these procedures.

Strokes. I hree basic types of strokes are used during instrumentation: the exploratory stroke, the scaling stroke, and the root planing stroke. Any of these basic-strokes max be activated by .1 pull or a push motion in a vertical, oblique, or horizontal direction (lig. -12-22). Vertical and oblique strokes are used most frequently. Horizontal strokes are used selectively on line angles or deep pockets that cannot be negotiated with vertical or oblique strokes. Ihe direction, length, pressure, and number of strokes necessary tor either scaling or root planing are determined by four major factors: gingival position and tone, pocket depth and shape, tooth ton-tour, and the amount and nature of the calculus or roughness.

The exploratory stroke is a light, "feeling" stroke that is used with probes and explorers to evaluate the dimensions of the pocket and to detect calculus and irregularities of the tooth surface. With bladed instruments such as the curette, the exploratory stroke is alternated with scaling and root planing strokes tor these same purposes of evaluation and detection. The instrument is grasped lightly and adapted with light pressure against the tooth to achieve maximal tactile sensitivity.

Ihe scaling stroke is a short, powerful pull stroke that is used with bladed instruments for the removal of both supragingival and subgingival calculus. Ihe muscles of the lingers and hands are tensed to establish a secure grasp, and lateral pressure is firmly applied against the tooth surface. The cutting edge engages the apical border of the calculus and dislodges it with a firm movement in a coronal direction. I he scaling motion should be initiated in the forearm and transmitted from the wrist to the hand with a slight Hexing of the lingers. Rotation of the wrist is synchronized with movement of the forearm. Ihe scaling stroke is not initiated in the wrist or fingers, nor is it carried out independently wit flout the use of the forearm.

It is possible to initiate the scaling motion by rotating the wrist and forearm or by flexing the lingers. I he use of wrist and forearm action versus finger motion has long been debated among clinicians. Perhaps the strong opinions on both sides should be the most valid indication that there is a time and a place for each. Neither method can be advocated exclusively, because a careful analysis of effective scaling and root planing technique i

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.